The invention relates generally to telecommunication networks and, more particularly, to a multi-function coding element which performs voice, fax and data coding and is suitable for use in an associated telecommunications network
In FIG. 1, the reference numeral 10 designates a conventional telecommunications network 10. As illustrated herein, the telecommunications network 10 includes a wireless system, for example, a cellular network and a wireline system, for example, the public switched telephone network (xe2x80x9cPSTNxe2x80x9d). The wireless system of the telecommunications network 10 further includes a mobile terminal. As illustrated herein, the mobile terminal 12 is a voice/fax/data terminal capable of operating in first, second and third modes in which voice, facsimile and data messages may be respectively transmitted or received.
The wireless system of the telecommunications network 10 also includes a base station 13 to which the mobile terminal 12 is coupled by an airlink. The base station 13 includes a base station controller 14 configured to transmit voice, fax and data messages to, and receive voice, fax and data messages from, the mobile terminal 12. While the wireless system illustrated in FIG. 1 shows a sole base station 13, it should be clearly understood that wireless systems typically include plural base stations, each having a base station controller incorporated therein. The base station controller 14 includes a voice coding (xe2x80x9cvocoderxe2x80x9d) element 16 which performs digital-to-analog (xe2x80x9cD/Axe2x80x9d) conversions on packets of digital voice data to produce analog voice tones. The vocoder element 16 also performs analog-to-digital (xe2x80x9cA/Dxe2x80x9d) conversions on analog voice tones to produce packets of digital voice data. More specifically, when set to operate in voice mode, the mobile terminal 12 will first advise the base station controller 12 to prepare to receive a voice message. The mobile terminal 12 will then transmit packets of digital voice data to the base station controller 34. There, the vocoder element 16 converts the received packets of digital voice data into analog voice tones for transmission to a mobile switching center (xe2x80x9cMSCxe2x80x9d) 20 coupled thereto. The vocoder element 16 may be embodied within a digital signal processor (xe2x80x9cDSPxe2x80x9d) which performs the D/A and A/D conversions of digital voice data and analog voice tones in accordance with respective sequences of instructions maintained thereby.
The MSC 20 directs the received analog voice tones to its destination which, for example, may be a second wireless terminal (not shown) coupled to the MSC 20, a wireless terminal coupled to a second MSC (also not shown), or, as illustrated herein, to a wireline terminal 26 located within the PSTN and coupled to the MSC 20 by an interexchange carrier (or xe2x80x9cIXCxe2x80x9d) 22 and a local exchange carrier (or xe2x80x9cLECxe2x80x9d) 24. As illustrated herein, the wireline terminal 26, like the mobile terminal 12, is a multi-mode terminal configured to transmit and receive voice, fax and data messages. Furthermore, while the wireline terminal 26 is shown as the destination of the voice signal originating at the mobile terminal 12, it should be further understood that the analog voice signal may be directed via other IXCs (not shown) and LECs (also not shown) of the PSTN to any of the multitude of wireline terminals included as part of the PSTN.
When set to operate in fax or data mode, the mobile terminal 12 will advise the base station controller 14 to prepare to receive a fax or data message. The mobile terminal 12 will then transmit either a digital facsimile message or a digital data message to the base station controller 14. In turn, the base station controller 14 transfers the received digital fax or digital data message to an interworking function (xe2x80x9cIWFxe2x80x9d) 18 which is coupled to the base station controller 14 and the MSC 20 and may be embodied as a DSP. If the IWF 18 receives packets of digital fax data from the base station controller 14, the IWF 18 converts the received digital fax data into analog modem tones. If, however, the IWF 18 receives a stream of digital data from the base station controller 14, the IWF 18 converts the received stream of digital data into an analog stream of digital data. The IWF 18 then passes the converted analog modem tones or analog data stream on to the MSC 20 where the message is handled in the manner previously described.
Voice, fax and data messages originating elsewhere on the telecommunications network 10 and having, as its destination, the mobile terminal 12, are handled in a reverse manner. Specifically, upon receiving analog voice tones destined for the mobile terminal 12 or other mobile terminal coupled to the base station controller 14, the MSC 20 will transmit the analog voice tones to the base station controller 14 where the vocoder element 16 will convert the analog voice tones signal into digital form. The resultant digital voice data produced thereby is then forwarded by the base station controller 14 to the mobile terminal 12. Conversely, when the MSC 20 receives analog modem tones or an analog data stream which originated elsewhere on the telecommunications network 10 and has, as its destination, the mobile terminal 12, the MSC 20 transfers the receive analog modem tones or analog data stream to the IWF 18 for conversion into digital format. After converting the received information into digital format, the IWF 18 transmits the resultant digital signal to the mobile terminal 12 via the base station controller 14
In one embodiment, the present invention is directed to a base station controller which includes a call control resource manager, a first coding resource and a second coding resource. The call control resource manager controls exchanges of messages between at least one mobile terminal and a mobile switching center (xe2x80x9cMSCxe2x80x9d). The first coding resource performs digital-to-analog (xe2x80x9cD/Axe2x80x9d) and analog-to-digital (xe2x80x9cA/Dxe2x80x9d) conversions for a first message type while the second coding resource performs D/A and A/D conversions for a second message type. In one aspect thereof, the base station controller may also include a third coding resource which performs D/A and A/D conversions for a third message type and, in a further aspect thereof, the first, second and third message types may be voice, facsimile and data, respectively. The coding resources may be embodied as software modules which reside on a multi-function coding element, which itself may be embodied as a digital signal processor.
In still further aspects of this embodiment, as well as in other embodiments thereof, the call control resource manager may receive digital messages from the mobile terminal, determine the message type for that digital message, call a selected one of the coding resources to perform a D/A conversion on the message and transmit the converted analog message to the MSC. The call control resource manager may also receive analog messages from the MSC, determine the message type for that analog message, call a selected one of the coding resources to perform an A/D conversion on the message and transmit the converted digital message to a selected mobile terminal.
In another embodiment, the present invention is directed to a telecommunications network which includes first and second mobile terminals, each configured for transmission and receipt of digital messages in at least one of voice, facsimile and data modes, a base station controller coupled to the first and second mobile terminals by respective airlinks and an MSC configured for transmitting analog messages to, and receiving analog messages from, the base station controller in each of the voice, facsimile and data modes. The base station controller includes a multi-function coding element which converts digital voice messages into analog voice messages, analog voice messages into digital voice messages, digital facsimile messages into analog facsimile messages, analog facsimile messages into digital facsimile messages, digital data messages into analog data messages and analog data messages into digital data messages. The multi-function coding element may be comprised of plural software modules, each for performing the above-listed conversions for a particular type of message while the base station controller may include a call control resource module which controls transmissions of messages between the first mobile terminal and the MSC, transmissions of messages between the second mobile terminal and the MSC and calls to the first, second and third software modules to perform conversions on voice, facsimile and data messages, respectively.
In another embodiment, the present invention is directed to a method for transferring a message from a mobile terminal to an MSC via a base station controller. In accordance with this embodiment of the invention, the mobile terminal first informs the base station controller of a message type for the message. After informing the base station controller of the message type, the mobile terminal transfers the message to a call control resource manager residing within the base station controller. Based upon the message type of the received message, the call control resource manager selects, from at least two resources residing within the base station controller, a resource for performing a D/A conversion of the message received from the mobile terminal. After the selected resource performs the D/A conversion of the received message, the call control resource manager transfers the converted message to the MSC. In related aspects of this embodiment, a first resource is selected for D/A conversions of voice messages, a second resource is selected for D/A conversions of facsimile messages and a third resource is selected for D/A conversions of data messages.
In still another embodiment, the present invention is directed to a method for transferring a message from an MSC to a mobile terminal via a base station controller. In accordance with this embodiment of the invention, the MSC first informs the base station controller of a message type for the message. After informing the base station controller of the message type, the MSC transfers the message to a call control resource manager residing within the base station controller. Based upon the message type of the received message, the call control resource manager selects, from at least two resources residing within the base station controller, a resource for performing an A/D conversion of the message received from the mobile terminal. After the selected resource performs the A/D conversion of the received message, the call control resource manager transfers the converted message to the mobile terminal. In related aspects of this embodiment, a first resource is selected for A/D conversions of voice messages, a second resource is selected for A/D conversions of facsimile messages and a third resource is selected for A/D conversions of data messages.